Reciprocating compressor

ABSTRACT

A reciprocating compressor is provided. The compressor includes a casing, a frame fixed to an inner circumferential surface of the casing, an oil storage portion formed in the frame, and an oil pocket formed at an outer circumferential surface of a piston and in communication with the oil storage portion. The piston reciprocates within a cylinder and pumps oil based on a change in volume of the oil in the oil pocket. Since an additional space to contain oil in the casing and an additional oil pumping device are not required, size of the compressor is reduced and structure is simplified. Furthermore, since oil is automatically pumped when the piston reciprocates, reliability of the compressor is enhanced.

This application claims priority to Korean Application No.10-2005-0129085, filed in Korea on Dec. 23, 2005, the entirety of whichis incorporated herein by reference .

BACKGROUND OF THE INVENTION

1. Field

The field relates to a compressor, and more particularly, to areciprocating compressor.

2. Background

In general, a compressor converts mechanical energy into compressiveenergy. Compressors may typically be categorized into a reciprocatingtype, a scroll type, a centrifugal type and a vane type. Reciprocatingcompressors may be further categorized into a horizontal typecompressor, and a vertical type reciprocating compressor.

Due to the need to provide for lubrication of various components,combined with the placement and orientation of the various components ofthe horizontal and vertical type reciprocating compressors, additionalspace is required in the casing to accommodate the oil. Further, in ahorizontal type reciprocating compressor, assembly is complicated due tothe large number of components of the oil pump, and oil is not smoothlyand continuously provided when oil viscosity is high. Likewise, thevertical orientation of the components of a vertical type reciprocatingcompressor makes it difficult to pump oil to the various components,thus decreasing reliability of the compressor.

Descriptions of reciprocating compressors and operation thereof can befound in, for example, U.S. Pat. Nos. 6,875,000, 6,875,001, and6,863,506, which are subject to an obligation of assignment to the sameentity, and the entirety of which is incorporated herein by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments will be described in detail with reference to thefollowing drawings in which like reference numerals refer to likeelements wherein:

FIG. 1 is a cross-sectional view of an exemplary vertical typereciprocating compressor having an oil pumping system as embodied andbroadly described herein;

FIG. 2 is a cross-sectional view of the exemplary compressor shown inFIG. 1 which illustrates an oil suction process as embodied and broadlydescribed herein;

FIG. 3 is a cross-sectional view of the exemplary compressor shown inFIG. 1 which illustrates an oil supply process as embodied and broadlydescribed herein;

FIG. 4 is a cross-sectional view of another exemplary vertical typereciprocating compressor having an oil pumping system as embodied andbroadly described herein;

FIG. 5 is a cross-sectional view of another exemplary vertical typereciprocating compressor having an oil pumping system as embodied andbroadly described herein; and

FIGS. 6-8 are exemplary installations of the exemplary compressors shownin FIGS. 1, 4 and 5.

DETAILED DESCRIPTION

A reciprocating compressor having an oil pumping system in accordancewith embodiments as broadly described herein is shown in FIG. 1.Although a reciprocating compressor, and particularly a horizontal typereciprocating compressor, is presented for ease of discussion, it iswell understood that an oil pumping assembly as embodied and broadlydescribed herein may be applied to other types of compressors and/orother applications which require fluid pumping as described herein. Theexemplary reciprocating compressor includes a casing 100, a suction pipeSP and a discharge pipe DP extending through the casing 100, areciprocating motor 200 installed in the casing 100 and having alinearly-reciprocating mover 230, and a compression unit 300 whichcompresses fluid as a piston 320 coupled to the mover 230 of thereciprocating motor 200 reciprocates with the mover 230.

The reciprocating motor 200 may include an outer stator 210 having awinding coil 211 thereon, an inner stator 220 installed in the outerstator 210 with a certain gap therebetween, and a mover 230 having amagnet 231 positioned in an air gap between the outer stator 210 and theinner stator 220.

The outer stator 210 is supported by first and second fixed frames 240and 250 coupled to opposite ends of the mover 230 by, for example, abolt or other suitable fastener, and is fixedly coupled to the casing100. The inner stator 220 may be pressed-fit to an outer circumferentialsurface of the first fixed frame 240.

In certain embodiments, the first fixed frame 240 has a disc shape withan outer diameter similar to that of the outer stator 220, with acylindrical fixing protrusion 241 which extends in a backward direction.The inner stator 220 is installed onto an outer circumferential surfaceof the first fixed frame 240, and a cylinder 310 is inserted into aninner circumferential surface of the first fixed frame 240.

An oil storage portion 242 for receiving oil at the time of assemblingthe compressor may be formed in the compressor. In the exemplarycompressor shown in FIG. 1, the oil storage portion 242 is formed in aring shape at an inner side surface of the first fixed frame 240. Otherlocations and shapes may also be appropriate. An oil passing hole 243may be formed, for example, at the fixing protrusion 241 of the firstfixed frame 240 so as to be connected to an oil pocket 323 formedbetween the cylinder 310 and the piston 320.

The mover 230 may be coupled to an outer circumferential surface of amovable frame 232 on which a plurality of magnets 231 is arrangedbetween the outer stator 210 and the inner stator 220. The movable frame232 may be formed in, for example, a cylindrical shape having two openedsides. A rear side of the two opened sides has portions which extendinward towards the center so as to be coupled to the piston 320 of thecompression unit 300 by, for example, a bolt or other suitable fastener.

The compression unit 300 may include a cylinder 310 inserted into andfixed to the fixing protrusion 241, a piston 320 coupled to the mover soas to reciprocate in a compression space 311 of the cylinder 310, aplurality of resonance springs 330 and 340 which elastically supportforward and rear sides of the piston 320, a suction valve 350 providedat an end surface of the piston 320 so as to open and close a suctionchannel 321 a of the piston 320, thereby regulating suction of fluid asnecessary, a discharge valve 360 mounted at a discharge side of thecylinder 310 which opens and closes the compression space 311, therebyregulating discharge of fluid, a valve spring 370 which elasticallysupports the discharge valve 360, and a discharge cover 380 which coversa discharge side of the cylinder 310, and in which the discharge valve360 and the valve spring 370 are received. The discharge cover 380 isinserted into a cover insertion hole 110 provided at an appropriate sideof the casing 100.

The cylinder 310 may have a cylindrical shape with smooth outer andinner circumferential surfaces. An oil passing hole 312 is formed in thecylinder 310 at a portion corresponding to the oil passing hole 243formed in the first fixed frame 240. The oil passing hole 312 receivesoil from the oil passing hole 243 and guides the oil towards an oilpocket 323 formed between the cylinder 310 and the piston 320. Thus, theoil passing hole 312 is positioned with a reciprocation range of aportion of the pistion 320 which includes the oil pocket 323.

A plurality of bearings 321 and 322 are provided at an outercircumferential surface of the piston 320, in sliding contact with aninner circumferential surface of the cylinder 310. The oil pocket 323has a predetermined volume so that a pressure difference can begenerated when the piston 310 is reciprocated due to its concave shapebetween the bearings 321 and 322.

In certain embodiments, the bearings 321 and 322 of the piston 320 havethe same outer diameter, as shown, for example, in FIGS. 2 and 3. Incertain embodiments, the oil pocket 323 is formed at a position higherthan the oil passing hole 243 so that a pressure difference can begenerated when oil is contained in the oil passing hole 243 of thecylinder 310. In certain embodiments, resonance springs 330 and 340 arecompression coil springs. One end of the front, or first resonancespring 330 may be fixed to a front side of a connection portion 332 ofthe piston 320, and another end of the first resonance spring 330 may befixed to the second fixed frame 250. One end of the rear, or secondresonance spring 340 may be fixed to a rear side of the connectionportion 332 of the piston 320, and another end of the second resonancespring 340 may be fixed to an inner circumferential surface of thecasing 100.

In certain embodiments, the suction valve 350 may include a fixedportion 351 which remains fixed to an end surface of the piston 320, andan opening/closing portion 352 which opens and closes the suctionchannel 321 a of the piston 320. In certain embodiments, the dischargevalve 360 may be formed of, for example, an engineered plastic material.Other materials may also be appropriate. A compression surface of thedischarge valve 360 may be detachably coupled to an end surface of thecylinder 310 so as to be opened and closed. A rear surface of thecompression surface may have a semi-spherical shape, as shown, forexample, in FIG. 1, or other shape as appropriate.

In certain embodiments, valve spring 370 may be, for example, acylindrical or a conical compression coil spring. One end of the valvespring 370 may be fixed to the rear surface of the compression surfaceof the discharge valve 360, and another end thereof may be fixed to aninner surface of the discharge cover 380, as shown, for example, inFIG. 1. When the valve spring 370 has a conical shape, a relatively wideside of the valve spring 370 may be fixed to the discharge cover 380 toprovide stability.

In certain embodiments, discharge cover 380 may form a single dischargespace 381, as shown, for example, in FIG. 1. In alternative embodiments,the discharge cover 380 may form a plurality of discharge spaces (notshown). The discharge cover 380 is installed so that a portion of thedischarge cover which defines the discharge space 381 is exposed throughthe cover insertion hole 110 of the casing 100. A coupling flangeportion 382 formed at an outer circumferential surface of an opened sideof the discharge cover 380 may be hermetically coupled to an outersurface of the first fixed frame 240.

When power is supplied to the winding coil 211 fixed to the outer stator210, a flux is generated between the outer stator 210 and the innerstator 220. This flux causes the mover 230, which is positioned betweenthe outer stator 210 and the inner stator 220, to be continuouslyreciprocated along a direction of the flux. Reciprocation of the mover230 causes the piston 320 coupled to the mover 230 to be accordinglyreciprocated in the cylinder 310, and a volume of the compression space311 formed between the cylinder 310 and the piston 320 is changed. As aresult, fluid is sucked into the compression space 311, compressed, andthen discharged.

As shown in FIG. 2, when the piston 320 performs a forward motion(compression stroke), a volume (A) of the oil pocket 323 is decreased,thus increasing pressure in the oil pocket 323. Then, as shown in FIG.3, when the piston 320 performs a backward motion (suction stroke), avolume (B) of the oil pocket 323 is decreased, thus lowering pressure inthe pocket 323 and thereby generating a pressure difference. A suctionforce is generated at the oil pocket 323 due to the pressure difference.The oil contained in the oil storage portion 242 of the first fixedframe 240 is sucked into the oil pocket 323 via the oil passing hole 243formed in the first fixed frame 240 and the oil passing hole 312 formedin the cylinder 310. Then, the oil provides for lubrication between thecylinder 310 and the piston 320 by contacting an outer circumferentialsurface of the bearings 321 and 322 of the piston 320 and/or an innercircumferential surface of the cylinder 310 when the piston 320 isreciprocated.

In this first embodiment, the oil pocket 323 is formed only on an outercircumferential surface of the piston 320. However, in accordance withthe second and third embodiments shown in FIGS. 4 and 5, respectively, amovable oil pocket 324 may be formed on the outer circumferentialsurface of the piston 320, and a fixed oil pocket 313 may be formed onthe inner circumferential surface of the cylinder 310. The fixed oilpocket 313 and the movable oil pocket 324 may be formed so as to extendhigher than the oil passing holes 243 and 312.

In certain embodiments, outer diameters D1 and D2 of the bearings 321and 322 positioned on opposite sides of the pocket may be equal, asshown, for example, in FIG. 5. In alternative embodiments, outerdiameters D1 and D2 may be different, as shown, for example, in FIG. 5.

When the fixed oil pocket 313 is formed at the cylinder 310 and themovable oil pocket 324 is formed at the piston 320, an oil pumpingprocess is similar to the aforementioned process, and thus a detailedexplanation is omitted.

In a compressor as embodied and broadly described herein, the oilstorage portion 242 is formed between the frame 240 and the cylinder310, and the oil pocket 323 or pockets 313, 323 which generates apressure difference is formed between the cylinder 310 and the piston320. The oil inside the oil storage portion 242 is pumped between thecylinder 310 and the piston 320 by the pressure difference generated inthe oil pocket 323 or pockets 313, 324. Thus, a compressor as embodiedand broadly described herein does not require additional space tocontain oil therein, nor an additional oil pumping device. Accordingly,a size of the compressor can be minimized, and a structure thereof canbe simplified, thereby improving an assembly process.

When the piston is reciprocated, oil is pumped thus generating anincreased pumping force. Furthermore, since oil can be pumped only ifthe piston is reciprocated, a reliability for the oil pumping operationis enhanced.

A compressor having an oil pumping system as embodied and broadlydescribed herein has numerous applications in which compression offluids is required, and in different types of compressors. Suchapplications may include, for example, air conditioning andrefrigeration applications. One such exemplary application is shown inFIG. 6, in which a compressor 610 having an oil pumping assembly asembodied and broadly described herein is installed in arefrigerator/freezer 600. Installation and functionality of a compressorin a refrigerator is discussed in detail in U.S. Pat. Nos. 7,082,776,6,955,064, 7,114,345, 7,055,338 and 6,772,601, the entirety of which areincorporated herein by reference.

Another such exemplary application is shown in FIG. 7, in which acompressor 710 having an oil pumping assembly as embodied and broadlydescribed herein is installed in an outdoor unit of an air conditioner700. Installation and functionality of a compressor in a refrigerator isdiscussed in detail in U.S. Pat. Nos. 7,121,106, 6,868,681, 5,775,120,6,374,492, 6,962,058, 6,951,628 and 5,947,373, the entirety of which areincorporated herein by reference.

Another such exemplary application is shown in FIG. 8, in which acompressor 810 having an oil pumping assembly as embodied and broadlydescribed herein is installed in a single, integrated air conditioningunit 800. Installation and functionality of a compressor in arefrigerator is discussed in detail in U.S. Pat. Nos. 7,032,404,6,412,298, 7,036,331, 6,588,228, 6,182,460 and 5,775,123, the entiretyof which are incorporated herein by reference.

An object is to provide a reciprocating compressor with an oil supplyingdevice having a high reliability, the compressor being capable ofreducing production cost with a small size and a small number ofcomponents.

To achieve these and other advantages, and in accordance embodiments asbroadly described herein, there is provided a reciprocating compressor,including a frame for supporting a stator of a reciprocating motorhaving a reciprocated mover, a cylinder insertion-fixed to the frame andhaving one or more oil passing holes for passing oil in a radialdirection thereof, and a piston slidably inserted into the cylinder thusto be coupled to the mover, and having an oil pocket on an outercircumferential surface thereof, the oil pocket connected to the oilpassing hole of the cylinder thus to generate a pressure difference dueto a volume change.

In accordance with another embodiment as broadly described herein, thereis provided a reciprocating compressor, including a frame for supportinga stator of a reciprocating motor having a reciprocated mover, acylinder insertion-fixed to the frame, having one or more oil passingholes for passing oil in a radial direction thereof, and having a fixedoil pocket concaved at an inner circumferential surface thereofconnected to the oil passing hole, and a piston sidably inserted intothe cylinder thus to be coupled to the mover, and having a movable oilpocket concaved at an outer circumferential surface thereof so as togenerate a pressure difference due to a volume change together with thefixed oil pocket of the cylinder.

In accordance with another embodiment as broadly described herein, thereis provided a reciprocating compressor, including a casing, a framefixedly coupled to an inner circumferential surface of the casing, andhaving an oil storage portion concaved at an outer circumferentialsurface thereof, a reciprocating motor having a stator fixedly coupledto the frame, and a mover reciprocated in a vertical direction, acylinder insertion-fixed to the frame and having one or more oil passingholes connected to the oil storage portion of the frame for passing oil,and a piston slidably inserted into the cylinder thus to be coupled tothe mover, and having an oil pocket at a contact surface with thecylinder, the oil pocket connected to the oil passing hole of thecylinder for pumping oil of the oil storage portion with generating apressure difference due to a volume change.

Any reference in this specification to “one embodiment,” “an exemplary,”“example embodiment,” “certain embodiment,” “alternative embodiment,”and the like means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment as broadly described herein. The appearancesof such phrases in various places in the specification are notnecessarily all referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with any embodiment, it is submitted that it is within thepurview of one skilled in the art to affect such feature, structure, orcharacteristic in connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, numerous variations andmodifications are possible in the component parts and/or arrangements ofthe subject combination arrangement within the scope of the disclosure,the drawings and the appended claims. In addition to variations andmodifications in the component parts and/or arrangements, alternativeuses will also be apparent to those skilled in the art.

1. A compressor, comprising: a frame configured to support areciprocating motor having a stator and a mover; a cylinder insertedinto and coupled to the frame, wherein the cylinder and the frame eachhave at least one passage formed in a respective radial directionthereof which are configured to allow fluid to flow therethrough; and apiston configured to be slidably inserted into the cylinder and to becoupled to the mover, wherein the piston comprises a pocket formed on anouter circumferential surface thereof, wherein the pocket is connectedto the at least one passage formed in the cylinder so as to generate apressure difference therebetween based on a volume of fluid in thepocket.
 2. The reciprocating compressor of claim 1, wherein thecompressor comprises a horizontal or a vertical reciprocatingcompressor.
 3. The reciprocating compressor of claim 1, wherein astorage portion configured to receive a predetermined amount of fluidtherein as formed as a recess in the frame, and wherein the at least onepassage formed in of the cylinder is in communication with storageportion.
 4. The reciprocating compressor of claim 3, wherein the atleast one passage formed in the frame provides for fluid communicationbetween the storage portion and the at least one passage formed in thecylinder.
 5. The reciprocating compressor of claim 1, wherein an innercircumferential surface of the cylinder is in sliding-contact an outercircumferential surface of the piston which excludes the pocket.
 6. Thereciprocating compressor of claim 1, wherein a vertical length of thepocket is greater than a diameter of the at least one passage formed inthe cylinder, and wherein an upper end of the pocket is positionedhigher than the at least one passage formed in the cylinder.
 7. Thereciprocating compressor of claim 1, wherein the at least one passageformed in the cylinder is positioned within a reciprocation range of thepocket.
 8. A reciprocating compressor, comprising: a frame configured tosupport a reciprocating motor having a mover and a stator; a cylinderinserted into and coupled to the frame, wherein the cylinder has atleast one passage formed in a radial direction thereof, and a fixedpocket formed as a recess in an inner circumferential surface thereofwhich is in communication with the at least one passage formed in thecylinder; and a piston coupled to the mover and configured to beslidably inserted into the cylinder, wherein the piston comprises amovable pocket formed as a recess in an outer circumferential surfacethereof, wherein the moveable pocket and the fixed pocket are configuredto generate a pressure difference due to a corresponding change volume.9. The reciprocating compressor of claim 8, further comprising a fluidstorage portion formed as a recess in the frame, wherein the at leastone passage formed in the cylinder is positioned proximate the storageportion.
 10. The reciprocating compressor of claim 9, further comprisinga passage formed in the frame which extends between the storage portionand the at least one passage formed in the cylinder so as to provide forfluid communication therebetween.
 11. The reciprocating compressor ofclaim 8, wherein an inner circumferential surface of the cylinder whichexcludes the fixed pocket is in sliding contact with an outercircumferential surface of the piston which excludes the moveablepocket.
 12. The reciprocating compressor of claim 8, wherein an outerdiameter of the piston is substantially uniform except for a portionthereof which forms the moveable pocket, and wherein an inner diameterthe cylinder varies such that an inner circumferential surface of thecylinder which excludes the fixed pocket maintains sliding-contact withan outer circumferential surface of the piston which excludes themoveable pocket.
 13. The reciprocating compressor of claim 8, wherein alength of the fixed pocket and a length of the moveable pocket in avertical direction are each greater than a diameter of the at least onepassage formed in the cylinder, and wherein upper ends of the fixed andmoveable pockets are positioned higher than the at least one passageformed in the cylinder.
 14. The reciprocating compressor of claim 8,wherein the at least one passage formed in the cylinder is positionedwithin a reciprocation range of the fixed and moveable pockets.
 15. Areciprocating compressor, comprising: a casing: a frame coupled to aninner circumferential surface of the casing, comprising a fluid storageportion formed as a recess along an outer circumferential surfacethereof; a reciprocating motor having a stator coupled to the frame anda mover configured to reciprocate in a vertical direction; a cylinderfixed to the frame and having at least one passage in communication withthe storage portion of the frame; a piston coupled to the mover andconfigured to be slidably inserted into the cylinder; and a pocketformed at either the cylinder or the piston so as to be in communicationwith the at least one passage formed in the cylinder, wherein the pocketis configured to generate a pressure difference due to a change involume of a fluid in the pocket when the piston is reciprocated.
 16. Thereciprocating compressor of claim 15, wherein the storage portion has aring shape.
 17. The reciprocating compressor of claim 15, wherein the atleast one passage formed in the cylinder is positioned within areciprocation range of the pocket.
 18. The reciprocating compressor ofclaim 15, wherein the pocket is formed in the piston, and wherein anouter diameter of the piston is substantially uniform except for aportion thereof which forms the pocket, and wherein an inner diameter orthe cylinder is substantially uniform such that an inner circumferentialsurface thereof maintains sliding-contact with an outer circumferentialsurface of the piston which excludes the pocket.
 19. The reciprocatingcompressor of claim 15, wherein the pocket is formed in the piston, andwherein an outer diameter of the piston varies, and wherein an innerdiameter of the cylinder varies corresponding to the outer diameter ofthe piston such that an inner circumferential surface of the cylindermaintains sliding-contact with an outer circumferential surface of thepiston which excludes the pocket.
 20. The reciprocating compressor ofclaim 15, wherein a vertical length of the pocket is greater than adiameter of the at least one passage formed in the cylinder, and whereinan upper end of the pocket is positioned higher than an upper end of theat least one passage.